AI Voice Agent Cost Calculator
Estimate per-minute and monthly spend for AI voice agents across platforms, then pick the cheapest stack for your call volume.
| Provider | Platform | LLM | STT | TTS | Inbound tel. | Outbound tel. | $/min | Monthly |
|---|---|---|---|---|---|---|---|---|
| Bland AI | — | — | ||||||
| Retell AI | — | — | ||||||
| Vapi | — | — | ||||||
| Synthflow | — | — | ||||||
| OpenAI Realtime API + Twilio | — | — | ||||||
| Self-hosted stack | — | — |
All rates are editable estimates in USD per minute. Update them to match your actual vendor quotes.
Cheapest option
At your selected volume, the cheapest stack is — at roughly —/month.
This ignores seat fees, setup costs, and concurrency limits. Use it as a first-pass filter.
Concurrency estimate
With an average call duration of — min, you need roughly — concurrent lines to handle peak load.
Assumes even distribution across a 12-hour business day and Erlang C ~1.3x headroom.
How to use this estimate
- Adjust minutes and inbound/outbound mix to match your expected call traffic.
- Edit per-minute rates if you have vendor quotes or custom LLM/TTS choices.
- Add fixed platform seats, phone-number rental, and developer labor on top of these variable costs.
- Compare against your current human or outsourced call-center cost to find the breakeven point.
Cross-links: Agent Stack Builder, API Pricing Comparator, AI Startup Cost Calculator.
🤖 Use this tool in your agent
✓ Agent-ready codeCopy the snippet below into your agent, newsletter, or script. The tool page at hermesdispatch.dev/tools/ai-voice-agent-cost-calculator/ is the canonical contract: inputs, outputs, and formulas.
# Hermes Dispatch Tool — AI Voice Agent Cost Calculator
# Source: https://hermesdispatch.dev/tools/ai-voice-agent-cost-calculator/
# Description: Estimate monthly cost for an AI voice agent by minutes, provider, and concurrency.
# License: MIT (generated by hermesdispatch.dev)
#
# INSTALL:
# 1. Save this file as ~/.hermes/hermes-agent/tools/ai_voice_agent_cost_calculator.py
# 2. Restart Hermes or run /reset in a session
# 3. The tool auto-registers if Hermes uses auto-discovery of tools/*.py
#
# MANUAL REGISTRY (if auto-discovery is off):
# from tools.ai_voice_agent_cost_calculator import register
# register()
import json
DATA = {}
def _ok(result):
return json.dumps({"success": True, "data": result}, indent=2)
def _err(message):
return json.dumps({"success": False, "error": message}, indent=2)
TOOL_NAME = "ai_voice_agent_cost_calculator"
TOOLSET = "agents"
SCHEMA = {
"type": "function",
"function": {
"name": "ai_voice_agent_cost_calculator",
"description": "Estimate monthly cost for an AI voice agent by minutes, provider, and concurrency.",
"parameters": {
"type": "object",
"properties": {
"minutes_per_month": {
"type": "integer",
"description": "Total voice minutes per month."
},
"cost_per_minute": {
"type": "number",
"description": "Cost per minute in USD."
},
"concurrent_calls": {
"type": "integer",
"description": "Average concurrent calls."
},
"llm_cost_per_minute": {
"type": "number",
"description": "LLM/transport cost per minute in USD."
}
},
"required": [
"minutes_per_month"
]
}
}
}
def _run(args):
minutes = int(args.get("minutes_per_month", 0))
voice_rate = float(args.get("cost_per_minute", 0.05))
llm_rate = float(args.get("llm_cost_per_minute", 0.03))
voice_cost = minutes * voice_rate
llm_cost = minutes * llm_rate
total = voice_cost + llm_cost
return _ok({
"voice_cost": round(voice_cost, 2),
"llm_transport_cost": round(llm_cost, 2),
"total_monthly_cost": round(total, 2),
"cost_per_hour": round(total / max(minutes / 60, 1), 2)
})
def HANDLER(args):
try:
return _run(args)
except Exception as e:
return _err(str(e))
def register():
"""Manual registry hook. Import and call this to register with Hermes."""
try:
from tools.registry import registry
registry.register(
name=TOOL_NAME,
toolset=TOOLSET,
schema=SCHEMA,
handler=HANDLER,
)
except ImportError:
print("Hermes registry not found; skipping manual registration.")
if __name__ == "__main__":
# CLI smoke test
print(HANDLER({}))
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